Conventional high-frequency antennas are often cumbersome to manufacture. For example, antennas designed for 100 GHz bandwidths typically use machined waveguides as feed structures, requiring expensive micro-machining and hand-tuning. Not only are these structures difficult and expensive to manufacture, they are also incompatible with integration in standard semiconductor processes.
As is the case with individual conventional high-frequency antennas, beam-forming arrays of such antennas are also generally difficult and expensive to manufacture. Conventional beam-forming arrays require complicated feed structures and phase-shifters that are incompatible with a semiconductor-based design. In addition, conventional beam-forming arrays become incompatible with digital signal processing techniques as the operating frequency is increased. For example, at the higher data rates enabled by high frequency operation, multipath fading and cross-interference becomes a serious issue. Adaptive beam forming techniques are known to combat these problems. But adaptive beam forming for transmission at 10 GHz or higher frequencies specifically requires massively parallel utilization of A/D and D/A converters. Moreover, the matching networks used to couple the antenna elements to the receiver/transmitters in conventional beam-forming arrays make accurate management of the phase shift problematic.
Accordingly, there is a need in the art for inductively-coupled antenna arrays that enable high-frequency beam-forming techniques yet are compatible with standard semiconductor processes.